Exhaust steam injector



' March 3, 1936. E. RAWSON EXHAUST STEAM INJECTOR Filed 001;. 26, 1934 ATTORNEY Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE EXHAUST STEAM INJECTOR Application October 26, 1934, Serial No. 750,032

13 Claims.

The present invention relates to exhaust steam injectors and has particular reference to exhaust steam injectors adapted to feed locomotive boilers and to operate for such purpose upon live steam 5 when exhaust steam is not available. More specifically the invention relates to the control of steam admission to such injectors.

In the operation of injectors of the above character, the variations in the pressure of the ex- 11} haust steam available for use in the injector are very considerable, depending upon conditions of engine operation, and since injectors of this kind are relatively sensitive, the variations in exhaust I )steam pressure, if unregulated, are sufiicient to 15 produce unstable operation or failure of operation of the injector under certain conditions. At the same time, the primary advantage of using an exhaust steam rather than a live steam injector is the saving efiected due to condensing and returning to the boiler a part of the steam exhausted from the engine. The larger the amount of exhaust steam condensed and returned, the greater the saving. Consequently, it is desirable that a maximum amount of exhaust steam be condensed in the injector that can be condensed under a given set of operating conditions without endangering the stability of operation of the injector.

Heretofore, numerous different kinds of control systems and modes of control of injectors of this type have been proposed, but the systems heretofore proposed, while in the main being satisfactory, have certain weaknesses under particular operating conditions which it is desirable to avoid.

The general object of the present invention is to provide an improved form of control system whereby the weaknesses of previously proposed systems are eliminated, and to this end the control system according to the present invention provides a control for the exhaust steam supply which is responsive to different regulating impulses under diiferent conditions of injector operation as will hereinafter more fully appear from the ensuing description of suitable apparatus for carrying the invention into eifect.

In the accompanying drawing forming a part of this specification:

Fig. 1 is a more or less diagrammatic view partly in section of an injector and control apparatus embodying the invention;

Fig. 2 is a view partly in section and on an enlarged scale of a portion of the injector illustrated in Fig. 1; and

Fig. 3 is a more or less diagrammatic illustration of a form of control apparatus different from that shown in Fig. 1.

Referring now more particularly to Fig. 1, the injector indicated generally at I is of the socalled Metcalfe type, although it is to be under- 5 stood that the invention is not restricted in its application to injectors of this specific type. The injector comprises a body l2 providing a low pressure steam chamber Hi which supplies steam to a main steam nozzle it. Water is supplied through the supply pipe !8 to the usual water nozzle (not shown), and the jet produced by the steam and water is established in a combining tube 26, from which it passes to the delivery tube 22 and thence to the delivery chamber 24 of the injector and the delivery pipe 26. The gap between the combining and delivery nozzles communicates with an overflow chamber 28, which, as will be observed from Fig. 2, has an outlet controlled by an overflow valve 30, which contr-ols flow to the overflow pipe 32. In this type of injector, the pressure in the overflow chamber may be above atmospheric, while the injector is still within its range of stable operation, and in order to permit the injector to operate with posi- 25 tive overflow chamber pressure the overflow valve is automatically loaded by means of a plunger 34 exposed to delivery pressure from the chamber 24 and acting through lever 36 to seat valve 30 against overflow pressure when the injector is 30 in operation and delivery pressure has been established. Obviously, when the injector is not in operation valve 30 is free to open to permit the overflow necessary for the establishment of the jet, and when the injector breaks the release of the delivery pressure permits overflow from the injector.

For locomotive injectors operating on exhaust steam and delivering against comparatively high boiler pressure, it is desirable to supplement the low pressure operating steam with a small quantity of high pressure steam, termed supplementary steam, which is admitted through the supplementary steam nozzle 38. Further, in order to permit continuous injector operation regardless of the presence or absence of a supply of exhaust steam, automatic control systems are ordinarily employed whereby in response to suitable factors indicative of the presence or ab- 50' sence of exhaust steam, low pressure live steam, termed auxiliary steam, is automatically supplied to the injector when exhaust steam is not available and is automatically shut off when exhaust steam becomes available.

For purposes of illustration, the present invention is shown, but without limitation, as applied in conjunction with an injector control system of known form and of the type in which the change-over from exhaust steam operation to livesteam operation and vice versa is directly responsive to the presence or absence of exhaust steam in the supply conduit leading to the injector. In this system, a main steam supply pipe 40, leading from the locomotive cab or other point of control, supplies high pressure steam which is utilized for operating the injector and the control system. A passage 42 conducts supplementary steam to the nozzle 38 at all times when the injector is in operation. A branch 44 in which is located a choke port 46 supplies steam to a chamber 48 in which islocated a double faced automatic or changeover valve 50 which,

when in the position shown in the figure, is

seated to close the passage 52 for supplying auxiliary live steam through ports 54 to the low pressure steam chamber M. A passage 56 supplies high pressure steam to a chamber 58 in which is located the head of a relay valve 60 having a piston part located in the cylinder 62 in the valve housing. A passage 64 connects chamopen valve it against the closing action of spring detailed disclosure of this form of'apparatus.

ber 58 with the chamber above the change-over valve 50, and passage 66 is connected, by means of pipe 66, to a cylinder in the injector body in which piston 68 is located. Piston 68 acts to I2 to provide communication between the low pressure steam chamber Id of the injector and the exhaust steam supply pipe 74. The space below the piston attached to the relay valve 60 is connected by means of pipe 76 to a diaphragm valve indicated generally at ?8 and comprising a needle valve 86 arranged to either close the outlet end of pipe 76 or to connect the end of this pipe with the vent pipe The position of valve 80 is determined by the presence or absence of exhaust steam pressure in the diaphragm chamber 84, which is connected to the exhaust steam supply pipe "It by means of pipes 86 and 88.

The control apparatus thus described is known per se, and forms the subject matter of United States Patent No. 1,870,006 granted August 2, 1932 on the application of Malcolm Hard, to which patent reference may be had for a more For an understanding of the present invention however, the action of this form of control apthrough the passage 56 to the chamber above this piston and leaking past the piston to the paratus .may be summarized briefly as follows.

Assuming exhaust steam to be available, diaphragm valve 80 is closed due to the presence of exhaust steam in the chamber 64. Consequently steam cannot escape from the chamber below the piston of the relay valve 60, and high pressure live steam passing from the supply pipe 40 chamber below it produces an unbalanced pressure lifting the relay valve to its upper seat, thus placing passages 56 and 64 in communication so that high pressure steam reaches the upper side of the change-over valve 56 and closes it. High pressure steam flows from passage 64 through the pipe 66 to piston 68, which opens the exhaust valve 70. Upon failure of the exhaust steam supply pipe I6 is vented by diaphragm valve 60 and the release of pressure in the chamber below the relay valve piston causes this valve to shift its.

position so as to cut offcommunication between passages 56 and 64 and to ventthelatter passage ber 48 the pressure of the steam in this chamber,

is reduced by the throttling action of the choke port 46. Release of pressure in passage 64 further vents the pipe 66 leading to the exhaust valve piston and permits the exhaust valve to be closed under the influence of spring 12.

From the foregoing, the operation which takes place when exhaust steam is again available will .be evident.

From the above description, it will be apparent that the automatic and exhaust valves operate in alternation, and that the control system provides a supply of high pressure steam in the passage 64 that is available only when the injector is operating as an exhaust steam injector.

The apparatus for carrying the present invention into eflect in conjunction with a system of is connected by means of a suitable lever and link connection indicated at 92 to a regulating piston 94 located in a cylinder 96 and adapted to move against the action of a spring 98 so as to move the valve toward closed position upon the application of pressure to the upper face of the piston. The upper face of the piston is placed in communication by means of a pipe I00 with the interior of a control valve I02 in which is located a valve member I04 having at its ends piston like heads I06 and I08 adapted to slide in the cylindrical portion of the valve body. Valve member I04 is urged toward the right hand end of the valve body by means of spring H0 and the left hand. end of the valve body is vented by means of passage H2. The pipe 88 leading from the exhaust steam supply pipe is in communication with the interior of the valve body I02 to one side of the center thereof and a pipe I I4 connects the overflow chamber space 28 of the injector with the interior of the valve body I02 at the other side of the center. The right hand end of the valve body is connected by means of pipe I I6 with the pipe 66, which supplies operating steam to the exhaust valve piston. A restriction or choke orifice is advantageously placed in the pipe I00 which connects the control valve with the cylinder 96.

In the position of the apparatus shown in the figure, the' injector is operating on exhaust steam, which is the condition of operation encountered most frequently in actual practice. With the injector operating on exhaust steam, the high pressure steam supply which effects opening of the exhaust valve also provides the pressure necessary to hold the control valve member I04 to its left hand position against the action of spring H0. In this position pipes I00 and H4 are placed in communication and the outlet of pipe 88 is closed by the piston or plunger I06. Consequently, the piston 94 for regulating the position of the valve 90 is subject to the pressure existing in the overflow chamber of the in jector. This pressure is immediately indicative of the stability of operation of the jet, and if, for example, the injector is operating at a low enough delivery rate so that there is insufiicient water supplied to the injector to properly condense the amount of exhaust steam that would be supplied by unthrottled admission of exhaust steam, the rise in overflow pressure due to the unstable condition of the jet arising from an excess of exhaust steam, will act to provide throttling regulation of the supply of this steam. Conversely, if the injector jet is stable, the overflow pressure will be at or near its minimum value, and consequently the maximum amount of exhaust steam may be admitted to the injector so long as the jet remains in this condition. This is, of course, highly desirable, since, as previously pointed out, the maximum condensation of exhaust steam is one of the primary functions of the exhaust steam injector. With low or negative overflow pressure, valve 90 may be fully open. Since the pressure of auxiliary live steam, which is used in place of exhaust steam when exhaust steam is not available, does not ordinarliy fluctuate as does the pressure of exhaust steam, regulation of the supply of auxiliary live steam is not ordinarily required, although it may be employed if desired. Accordingly, in the present embodiment I have shown no means for effecting regulation of the admission of auxiliary live steam. When the exhaust steam supply fails due to stoppage of the engine, the exhaust valve 10 is closed due to the venting of the pressure in pipe 66, as previously explained. The venting of this pipe releases the pressure holding the control valve member I04 in its left hand position and under the influence of spring H0 this valve member moves to the right hand end of its stroke, in which position the outlet of pipe 88 is uncovered by the plunger I06 and the outlet of the pipe H4 is covered by the plunger I08. Thus, when the injector is not operating on exhaust steam, the overflow pressure control of the steam regulating valve 90 is made inoperative, and by placing pipes 88 and I00 in communication the control of the position of valve 90 is made responsive to exhaust steam pressure. Making the position of the exhaust steam regulating valve 90 dependent upon exhaust steam pressure may, at first glance, appear to be quite inconsistent with the assumption that the injector is operating as a live steam injector, since this assumption would seem to import a lack of exhaust steam with which to regulate the position of valve 90, and further, any regulation of the position of valve 90 would seem at first glance to be useless, since under the condition of live steam operation the exhaust valve 10 is closed. This apparently inconsistent and useless arrangement is, however, of great utility in meeting certain conditions which are the rather obscure reason for interruption of the operation of an injector of this kind when regulated by means of an overflow or like type of regulation.

In order to understand the utility of the above described arrangement, it is necessary to consider certain conditions of operation that arise in practice. In the first place, satisfactory operation of the injector on exhaust steam cannot be obtained when the exhaust steam is delivered from an engine operating so slowly that the exhaust steam is delivered with pronounced pressure pulsations, and there are also certain minimum exhaust steam pressures which will produce satisfactory operation. Consequently, the control systems are substantially uniformly set so that with the injector operating on live steam in the absence of exhaust steam, the change-over to exhaust steam when exhaust steam becomes available is not made until the exhaust steam pressure reaches a predetermined minimum value. When this value is reached and change-over occurs the steam is at sufliciently steady pressure to insure changeover without interruption of operation. Thus, it is not only possible but is an actually existing condition that exhaust steam may be present in the supply pipe 14 before change-over of the injector to exhaust steam operation may occur. It has been found in practice that very frequently when the change-over from live steam to exhaust steam operation occurs the conditions of operation of the engine are such that the engine is delivering large quantities of exhaust steam against a relatively high back pressure, so that exhaust steam is made available to the injector at relatively high pressure. When the injector is operating as a live steam injector, it is frequently the case that the injector is operated at or near minimum capacity, for when the engine is not operating the requirements for boiler feed water are frequently at a minimum. If, with the injector operating at minimum capacity as a live steam injector, change-over is suddenly made to exhaust steam operation with an unregulated supply of exhaust steam at high pressure being admitted to the injector, the excess steam may cause the jet to break before even as rapid a control as the overflow control can act to move the exhaust steam regulating valve to a proper throttling position. It is to avoid this contingency of the injector breaking upon change-over to exhaust steam operation under certain conditions that I provide the control arrangement whereby the exhaust steam regulating valve is positioned, prior to exhaust steam operation of the injector, so as to prevent the admission of too much exhaust steam at the time when change-over to exhaust steam operation occurs. When exhaust steam is first available in the pipe 14, it closes the diaphragm valve as previously explained. Some time must elapse before actuation of the relay valve and the change-over valve occurs, and during this period of time the exhaust steam pressure may act on the piston 94 to move the regulating valve 90 to a throttling position corresponding to the value of the exhaust steam pressure. In other words, the regulating Valve may be said to be pre-set to regulating position while the injector is still operating as a live steam injector. With the regulating valve thus pre-set, the exhaust steam is admitted to the injector when change-over occurs, at a pressure sufliciently low to insure against interruption of operation due to sudden admission of steam at much higher pressure than that of the auxiliary live steam upon which the injector had been operating prior to change-over.

In some instances, a choke, such as the choke H8 may be desirable in order to prevent sudden pressure change in the pipe I00 at the time when the control valve member 104 shifts in response to change of operation of the injector from live steam operation to exhaust steam operation.

It will be found that with the usual locomotive type injector delivering against the boiler pressures usually encountered, the positive overflow pressures to which the piston 94 is subjected in connection with overflow pressure regulation are of the same order as the exhaust steam pressures which make regulation of the piston of the valve 90 desirable. Consequently, it is possible as a practical matter to alternatively apply to the same valve regulating piston the pressures of the overflow and of the exhaust steam for the purposes described.

While I have shown and described above. in detail the application of the invention in conjunction with an overflow pressure control of the exhaust steam supply when the injector is operating on exhaust steam, the invention is not limited to this specific form of regulation, and in Fig. 3 there is shown an arrangement whereby the present invention may be employed in conjunction with a delivery temperature control. In this arrangement the control valve I02a is connected by means of pipe I00 to the cylin- (hr 96 as in the arrangement shown in Fig. 1, and the pipe I00 may have therein a choke IIB. Also, as in the arrangement previously shown, the end of the valve body is connected by means of a pipe I IS with a source of operating steam which is available when the injector is operating on exhaust steam. Pipe 88, leading from the exhaust steam supply pipe 14 is connected to the body of the valve I02a, but is connected so that its outlet is opposite the inlet of the pipe I 00. The body of the control valve is provided with a vent port I20 located so as to be covered by the plunger I080. of the valve member when the latter is in the position shown in the figure, and so as to be uncovered when the valve member shifts to its left hand position under the influence of steam admitted through pipe H6. The vent port I20 is controlled by a needle valve I22 which is in turn actuated by an expansion element I24 connected by pipe I26 to the thermostat element I28 located in the delivery chamber 24 of the injector.

This form of apparatus operates as follows. In the position of the apparatus shown in the figure, no pressure exists in pipe H6 and the injector is operating as a live steam injector. Under this condition of operation, pipes 88 and I00 are in communication and consequently the positon of valve is determined by the pressure of exhaust steam in the supply pipe I4. Upon shift of the injector to exhaust steam operation, shifting of the control valve member 34:1 to the left places pipes I90 and 88 and the Vent port I20 in communication with each other through the medium of the chamber within the valve body defined between the plungers l08ct. With the control valve member in this position, the exhaust steam pressure ceases to become the regulating factor, and instead the regulating factor becomes the degree of opening of the vent I20, which obviously is determinative of the pressure applied to the valve actuating piston 94 through the pipe I00. The size of port I20 is made such that if this port is fully opened, it can vent steam from the interior of the control valve housing as rapidly as it can be supplied through the relatively small pipe 88, and under these conditions of operation no pressure will exist in pipe I 00, and consequently valve 90 will be wide open.

a As the temperature of the delivery water increases to a value indicating too high a proportion of steam to water being admitted to the injector, the expansion of the thermostat element acts to progressively close the vent port I20 and produce regulating pressure in the pipe I 00. From this it will be evident that in this arrangement the exhaust steam is merely an operating medium and not per se a controlling medium, and it will be equally evident that another source of steam pressure might be employed in conjunction with the vent port rather. than ex- IElBa and haust steam. The use of exhaust steam, however, simplifies the construction and is advantageous on this account.

While I have shown a delivery temperature control in the embodiment of Fig. 3, in order to illustrate the fact that the invention is not lim-- ited in its application to only one form of injector control, I prefer to employ the overflow type of control, which I consider more satisfactory since it is more sensitive and is the quicker operating form.

It will be understood by those skilled in the art that the invention may be made use of with many different specific forms of apparatus including various different types of control systems, and it is accordingly to be understood as embracing all forms of apparatus falling within the scope of the appended claims when they are construed as broadly as is consistent with the state of the prior art.

What I claim is:

1. In exhaust steam injector apparatus of the type in which the injector is adapted to operate.

with live steam when exhaust steam is not available, means'for regulating the admission of exhaust steam to the injector alternatively in response to two different regulating impulses of which one is exhaust steam pressure, said means being constructed and arranged to be set, in re-' sponse to exhaust steam pressure when the injector is operating on live steam, to regulate the rate at which exhaust steam may flow to the injector upon shift to exhaust steam operation and to regulate flow of exhaust steam to the injector in response to the remaining regulating impulse when the injector is operating as an exhaust steam injector.

2. In exhaust steam injector apparatus of the type in which the injector is adapted to operate with live steam when exhaust steam is not available, means for regulating the admission of exhaust steam to the injector alternatively in response to overflow pressure or exhaust steam pressure, said means being constructed and arranged to be set, in response to exhaust steam pressure when the injector is operating on livev steam, to regulate the rate at which exhaust steam may flow to the injector upon shift to exhaust steam operation and to regulate flow of exhaust steam to the injector in response to overflow pressure when the injector is operating as exhaust steam injector.

3. In exhaust steam injector apparatus of the type in which the injector is adapted to operate with live steam when exhaust steam is not available, valve means for regulating the supply of exhaust steam to the injector, means responsive to a regulating impulse indicative of the stability of operation of the injector for controlling said valve means when the injector is supplied with exhaust steam and means responsive to exhaust steam pressure for controlling said valve means when the injector is operated with live steam only.

4. In exhaust steam injector apparatus of thetype in which the injector is adapted to operate with live steam when exhaust steam is not available, an exhaust steam supply conduit, a regulating valve in said conduit, and means for regulating the position of adjustment of said valve alternatively in response to different regulating impulses of which one impulse is exhaust steam pressure, said means being constructed and arranged to cause the position of adjustment of said valvev to be controlled by exhaust steam pressure only when the injector is operating as a live steam injector.

5. In an exhaust steam injector control system of the type adapted to automatically shift operation of the injector from live steam operation to exhaust steam operation and vice versa in accordance with the presence or absence of a suitable exhaust steam supply, means responsive to exhaust steam pressure for regulating the area for flow of exhaust steam to the injector, and means actuated by shift of operation of the injector to exhaust steam operation for rendering said first named means inoperative.

6. In apparatus of the character described, the combination with an injector control system having an exhaust steam regulating valve, of means for adjusting the position of said valve in response to exhaust steam pressure prior to admission of exhaust steam to the injector, means for rendering the first mentioned means inoperative when the injector is operating as an exhaust steam injector, and means for adjusting the position of said valve in response to a regulating impulse indicative of stability of injector operation when the first mentioned means is inoperative.

7. In exhaust steam injector apparatus of the character described, the combination with a control system having overflow pressure responsive valve means for regulating flow of exhaust steam to the injector, of means for rendering said Valve means independent of overflow pressure upon shift of the injector to live steam operation, and means for rendering said valve means responsive to exhaust steam pressure whenever it is independent of overflow pressure and exhaust steam pressure is available.

8. In exhaust steam injector apparatus, an exhaust steam supply passage, an exhaust steam regulating valve in said passage, pressure responsive means for actuating said valve, a first conduit for placing said pressure responsive means in communication with the interior of the injector, a second conduit for placing said pressure responsive means in communication with said exhaust steam passage, and means automatically responsive to shift of operation of the injector from live steam operation to exhaust steam operation and vice versa for alternatively placing said first conduit and said second conduit in communication with said pressure responsive means.

9. In exhaust steam injector apparatus of the type including a control system having a source of operating steam available only when the injector is operating as an exhaust steam injector, an exhaust steam supply passage, a regulating valve in said passage, pressure responsive means for controlling said valve, a first conduit for supplying exhaust steam to said pressure responsive means, a second conduit for transmitting pressure from the overflow chamber of said injector to said pressure responsive means, and a control valve the position of adjustment of which is determined by the presence or absence of pressure from said source for connecting said first conduit 6 with said pressure responsive means when the injector is operating as a live steam injector and for connecting said second conduit with said pressure responsive means when the injector is operating as an exhaust steam injector. 10

10. In exhaust steam injector apparatus including an injector of the type adapted to be operated by live steam when exhaust steam is not available, the combination with an automatic control system having an overflow pressure controlled valve for regulating flow of exhaust steam to the injector, of means responsive to exhaust steam pressure for presetting said valve in accordance with exhaust steam pressure prior to shift of operation of the injector from live steam operation to exhaust steam operation.

11. In exhaust steam injector apparatus, a control system having an exhaust steam supply passage and a regulating valve in said passage, pressure responsive means for actuating said valve, conduit means for placing said pressure responsive means in communication with the exhaust steam supply passage, a control valve in said conduit means, and means for modifying the pressure of exhaust steam transmitted through said control valve in accordance with the working conditions withinthe injector when the injector is operating on exhaust steam.

12. In the operation of an exhaust steam injector of the type adapted to operate on live 36 steam when exhaust steam is not available, that improvement which consists in utilizing pressure of exhaust steam to limit the pressure at which such steam is admitted to the injector when the injector shifts from live steam operation to ex- 40 haust steam operation and thereafter regulating the supply of exhaust steam to the injector in accordance with the working conditions within the injector so as to admit to the injector the maximum quantity of exhaust steam which the injector can utilize while operating as an exhaust steam injector.

13. In the operation of an exhaust steam injector of the type adapted to operate on live steam when exhaust steam is not available, that improvement which consists in utilizing pressure of exhaust steam to limit the pressure at which such steam is admitted to the injector when the injector shifts from live steam operation to exhaust steam operation and after the injector has shifted to exhaust steam operation, utilizing the overflow pressure of the injector to regulate the quantity of exhaust steam admitted to the injector.

EMANUEL RAWSON. 

